The roles of higher education institutions has been changing with the rise of massive open online courses (MOOCs) since 2011, and platforms such as Coursea, edX and Udacity are offering thousands of courses worldwide (Martin, 2012). Online courses are mostly organized as sequences of instructor-produced videos interspersed with other resources such as assessment problems and interactive discussion, and videos are central to the student learning experience in the current generation of MOOCs. Recently, diverse instructional strategies have been used to enhance learning outcomes for video-based courses, and the use of the advance organizer is one instructional approach to improve video quality and efficiency. Research questions addressed in this study included: 1) Is there any difference on learner achievement among groups with videos designed using different advance organizers? 2) Is there any difference on flow experience among groups with videos designed using different advance organizers? To explore these questions, experimental videos were adapted from a Taiwan MOOC and were redesigned according to the research needs. This work not only expands the theories of video-based learning but also serves as a reference for future designers to create a better MOOC environment.

MOOC videos, which are created as one instructional approach for university instructors, support the establishment of theory and practice for new knowledge delivery. These videos are usually presented via instructors' talking heads, conversation, interviews, seminars, presentation slides with voice, animation or demonstration (Guo et al., 2014). Despite the advantages of online video-based courses, this type of course has been greatly criticized for its low learner engagement, resulting in dramatic low course and video completion rates (Hew & Cheung, 2014). Researchers claimed that the lecturer's instructional approaches used in the video might be influential on learner engagement (Margaryan et al., 2015), but relative studies were limited.

The use of the advance organizer is one critical approach to enhance instructional quality and efficiency. The advance organizer is a strategy which serves as a cognitive bridge or scaffold to help learners make links between what they know and what is to be learned (Ausubel, 2000), and it is provided by words, diagrams, charts, or even animation. Advance organizers can be categorized as the following types:

• The expository advance organizer gives learners a broad idea of the lesson's purpose before the lesson begins.
• The narrative advance organizer uses a story to prepare learners for instruction.
• The graphic organizer offers visual representations to help learners structure information.
• The comparative organizer compares two things that are alike in some way (Ylvisaker, 2006).

Among all, the graphic organizer is an approach that organizes information into categories, and it is usually presented in the form of the graphic organizer including the mind map (main-idea web), Venn diagram and sequence chart. Researchers have argued that the advance organizer promotes second language significantly (Ambard & Ambard, 2012), and it also facilitates students' conceptualization in science (Domin, 2008). The advance organizer is one effective way for students to comprehend instructional content in the printed-based environment. It is very likely that this support is just as effective in digital form, especially for video-based learning.

To better explore the impact of advance organizer on online video-based learners, this study targeted learner achievement as well as flow experience as the measurement. The term 'flow' was used to describe the most positive and enjoyable feelings in human. When in the flow state, people become absorbed in their activities while irrelevant thoughts and perceptions are screened out (Csikszentmihalyi, 1975). Creating a learning environment with an atmosphere that allows for flow and growth, Csikszentmihályi argued, can increase the happiness and achievement of learners. Chen (2006) defined the symptoms and phenomena of flow state possessing nine dimensions: 1) immediate feedback, 2) clear goals, 3) merger of action and awareness, 4) concentration, 5) sense of potential control, 6) loss of self-consciousness, 7) time distortion, 8) tele presence, and 9) positive affects. Chen (2006) developed a survey to measure flow experience based on these nine dimensions, and used it in this study as the main instrument. The flow instrument was a practical tool for evaluating the efficiency of online videobased learning and it was also viewed as one critical index for learner engagement (Wang, 2017).

There is consensus that creating effective environments with the advance organizer can help learning (Bulgren & Schumaker, 2006), but there is very little research on how it works in online learning especially in the MOOC environment. This study addresses this gap by examining the video design and explored influences of advance organizer on learners.

2.1. Experimental Material

The experimental videos were adapted from a Taiwan MOOC Digital Content Production (course delivered in fall 2018 by the researcher). The original course was a fourteen-week online course that aimed to improve learners' knowledge and skill for mobile photography, digital imaging and video editing. One video clip about formats of digital films was selected as the experimental material, and this video was reproduced based on research needs.

2.2. Treatment

The video clip was redesigned and recorded into three versions with different advance organizers: 1) no advance organizer for the video (Group1), 2) a main-idea web as the advance organizer for the video (Group2), 3) a sequence chart as the advance organizer for the video (Group3). For the video provided in Group1, the instructor lectured from the beginning of the video to the end without any graphic organizer as the facilitator (Figure 1).

Figure 1. No Advance Organizer for the Video

The video provided in Group 2 was designed with a mainidea web as the advance organizer. The instructional content was categorized as a main-idea web and presented as a static graphic to learners before the instructor started to explain. The graphic organizer stayed on screen about twenty seconds and then lecture began (Figure 2).

Figure 2. A Main-Idea Web as Advance Organizer for the Video

The video provided in Group 3 was designed with a sequence chart as the advance organizer. The instructional content was categorized as a sequence chart and presented as a static graphic to learners before the instructor started talking. The graphic organizer stayed on screen about 20 seconds and then went over to the lecture (Figure 3).

Figure 3. A Sequence Chart as Advance Organizer for the Video

The length of all video clips were about eight minutes. The content delivered from all versions of videos were the same but the advance organizers in the video opening were different.

2.3 Procedure

The data collection was conducted in the 2018 fall semester. Sixty-eight students were voluntarily recruited from two colleges in southern Taiwan for the study and were randomly put into three treatment groups. Participants had a ten-minute pre-test composed of ten questions on content. Then, they were assigned into different treatment groups for watching the video clips, which took about eight minutes. Finally they were asked to do a post-test and flow survey. After the survey, six participants were selected randomly for the informal interview. They went through different design of the advance organizers and expressed their thoughts about the videos. Figure 4 shows the experimental procedure.

Figure 4. Experimental Procedure

2.4 Measurement

The measurement used in this study included the achievement tests (pre-test and post-test) as well as the flow experience survey. Both the pre-test and post-test were designed with ten multiple-choice questions based on the instructional material. Questions had the same difficulty with expert validity. The flow experience instrument used in this study was a Likert-scale measurement developed by Chen (2006), which was based on Csikszentmihalyi's flow theory. Nine dimensions (immediate feedback, clear goals, merger of action and awareness, concentration, sense of potential control, loss of self-consciousness, time distortion, telepresence, and positive affects) were included and the reliability for the measurement was 0.73, which was accepted as a moderate reliable scale and showed the consistency for question items.

Learners' pretest scores were first examined to see if there was any prior-knowledge difference among groups. The results showed that no score difference existed. That is, students' prior knowledge was equal among the three groups. However, in the post-test scores, differences did exist among the three groups. The results showed that students watching the video with a sequence chart as the advance organizer performed significantly better than the other two groups. Table 1 shows the descriptive and inferred statistics for learning achievement.

Table 1. Descriptive and Inferred Statistics for Learning Achievement

Learners' flow experience was then examined in nine dimensions. The results showed that there was a significant difference on learners' loss of self-conscious and positive affect among the three groups. Students who watched the video with a sequence chart as the advance organizer performed significantly better. Table 2 shows the descriptive and inferred statistics for learners' flow experience.

Table 2. Descriptive and Inferred Statistics for Flow Experience

This study explored the impact of advance organizer design for MOOC videos on students learning achievement and flow experience. The results showed that significant differences existed on both learner achievement and flow experience among groups. It was found that the video designed with a sequence chart as the advance organizer benefitted learning achievement and flow experience. The detailed findings included:

• Learners who watched the video with a sequence chart as the advance organizer had significantly better on post-test scores than learners who were provided with a main-idea web as the advance organizer and with no advance organizer.
• Learners who watched the video with a sequence chart as the advance organizer performed significantly better on loss of self-conscious than learners who were provided with a main-idea web as the advance organizer.
• Learners who watched the video with a sequence chart as the advance organizer performed significantly better on positive affects than learners who were provided with a main-idea web as the advance organizer and with no advance organizer.

Several possible reasons were uncovered through the informal interviews for the superiority of using the advance organizer as the facilitator in video-based learning, particularly in the form of the sequence chart. First, learners mentioned that the visual design for the sequence chart was better than the design of the main-idea web.

“…I'd like to have an organizer before the lecture. The sequence chart has better visual effects in terms of colors and layout… I feel comfortable while reading it…” (student A's reflection)

“…I prefer the sequence chart because of its simple design and colorful graphics. It makes me enjoyable... I am very focused and engaged in watching videos…” (student B's reflection).

Second, learners mentioned that the sequence chart provided a linear and systematic way for learners to organized information.

“… comparing with the main-idea web, sequence chart is simpler for me to read… this approach is used in many textbook to organize information, so we are familiar with it…” (student C's reflection)

“…the sequence chart is clear to deliver information on development of something. Content in this unit is about the development of the film format, and the sequence chart plays an important role to give me a pre-course overview…” (student D's reflection)

“…it's very appropriate to teach historical changes or historical events using a sequence chart…I would like to have this chart before going to lecture…” (student D's reflection).

Most learners showed positive attitude to the use of the advance organizer in videos, especially when designing it with the format of a sequence chart. The findings aligned with the claiming that the use of advance organizer is beneficial to the learner (Bulgren & Schumaker, 2006). Researchers have reported empirical findings on learners' higher achievement with the use of advance organizer in the second language and science learning (Ambard & Ambard, 2012; Domin, 2008). This study expands the theoretical framework by shifting the content to a new course in higher education.

This paper examined the effect of the advance organizer for MOOC videos on students' learning achievement and flow experience. The treatment in this study was the advance organizer designed as three types:

• No advance organizer for the video.
• A main-idea web as the advance organizer for the video.
• A sequence chart as the advance organizer for the video.

The results showed significant differences on both learner achievement and flow experience among groups. In the future, improvement will be made in the video design, expanding the sample size and exploring its effects on learning. Further studies with diverse treatment groups will be conducted soon to verify findings.

Acknowledgement

This project was sponsored by the Ministry of Science and Technology (Taiwan), under research grant No. 108-2511- H-415-008.